EBay has banned the sale of smalltooth sawfish — the first U.S. marine fish ever listed under the Endangered Species Act — and agreed to have conservation groups help monitor the ban, one of the partners announced this week.

Live sawfish, which are a shark-like ray, were not being sold on eBay but their tooth-studded snouts had found a niche as curios and trophies.

“Sawfish are a highly endangered species and yet continue to be traded around the world,” Sonja Fordham, shark conservation specialist for The Ocean Conservancy, said in a statement Monday announcing the decision. “We welcome eBay’s action as an important step towards preventing smalltooth sawfish extinction and putting this species on the long road to recovery.”

A 2004 study of eBay sales of sawfish snouts found about 20 transactions a month. Prices averaged $119 a snout but went as high as $1,242.

Most buyers were in the United States (40 percent), followed by the United Kingdom (14 percent) and Australia (8 percent). Most sellers were in the United States (33 percent), then Australia (26 percent) and the U.K. (23 percent).

“In one instance, a seller used a picture from Mote Marine Lab's Web site — the same site that talks about how they are an endangered species,” said Ocean Conservancy spokesman Tom McCann.

Other conservation groups have criticized eBay for tolerating the sales of parts from other endangered species, including sea turtle shells and elephant ivory. EBay has policy guidelines tied to U.S. and international conventions, but critics say buyers and sellers either aren’t aware or flout the policies.

The conservancy said it as well as the Mote Marine Laboratory would work with eBay to enforce the smalltooth sawfish ban.

The group noted that in U.S. waters smalltooth sawfish once ranged from Texas to New York, but now are only regularly found in a few protected areas of Florida.

The U.S. population has declined by as much as 99 percent since European settlement, the conservancy said, due mainly to loss of habitat and being accidentally caught by fishermen going after other species.

The National Marine Fisheries Service is is finalizing a recovery plan for smalltooth sawfish that should be ready for public comment later this year, the conservancy said.

The species plight is not limited to the United States. All species of sawfish worldwide are considered “critically endangered” by the World Conservation Union.